1. Field of the Invention
The present invention relates generally to piston operated devices, and, more particularly, to motors, expanders, compressors, and hydraulics having rotating cylinders.
2. Background Art
The world is running on internal combustion engines. For over a century, internal combustion gasoline and diesel engines, turbines, and Stirling engines have been used. More recently the Wankel engine was developed.
The response time of turbines and Stirling engines is too slow for automobile use. Wankel engines have fallen out of favor. Gasoline and diesel motors have been the mainstays of the auto industry in spite of low efficiency. Considering the combustion temperatures in these motors, the theoretical efficiency (Carnot efficiency) should be above 70%. Typically the efficiency of today""s automobile motors is 25%. One of the chief reasons for the low efficiency is the high-energy losses due to sliding friction of the pistons against cylinder walls. This loss is turned into heat and carried away by the cooling water around the engine block.
Piston engines have been functioning since the early days of steam powered devices. Standard internal combustion engines are everywhere. Variations of the internal combustion engine are the Wankel motor and rotary piston engine such as that described in U.S. Pat. Nos. 3,741,694. 5,813,372 describes a rotary piston engine in which internal friction is reduced since the pistons do not touch the cylinder walls. Only piston rings touch the walls. The cylinders and pistons rotate around an axis and rely on a sliding valve arrangement to open ports for intake and exhaust. The difficulty with this device is that the large sliding surfaces of the head past the valve ports supply a large amount of friction.
U.S. Pat. No. 5,803,041 describes a rotary engine in which linear piston motion is translated into rotary motion of the cylinder.
U.S. Pat. No. 5,138,994 describes a rotary piston engine in which a rectangular piston rotates in an annular cavity. As the piston rotates continuously in one direction, a gate that blocks the annular cavity opens once during each revolution of the piston to allow the piston to pass. The piston is connected to a central shaft by a disk that penetrates the inner cylindrical wall of the cavity. The problem with this device is that large sliding friction forces occur all the way around the rotary piston as it rubs against cylinder walls. Additional friction occurs where the disk penetrates the cylindrical wall.
U.S. Pat. No. 4,938,668 shows a rotating piston design in which two sets of rotating pistons oscillate together and apart forming cavities that change in volume as the two sets of pistons rotate around a common shaft. A cam system provides the thrust that drives the shaft. The pistons slide against an end plate in which are located intake and exhaust ports. This device would also have large sliding friction as the rotating pistons rub against the outer cylinder and against the end plates where the ports are located.
U.S. Pat. No. 4,002,033 is a rotary displacer that has a rotary-abutment sealing rotor that rotates against the main rotary piston. However, there is a slight space between the sealing rotor and the rotary piston, since the surface speeds are different. They both rotate at the same angular velocity, but since their diameters are different, the abutting surface velocities are different. The rotary piston does not touch the walls of the cylinder to eliminate sliding friction. This allows for excessive blow-by. To reduce the blow-by, grooves are formed in the piston walls to create turbulence in the gas flow. Blow-by is still a problem with this design.
U.S. Pat. No. 4,099,448 shows, rotating vanes that have rotating gears about the axes that keep the vanes synchronous. Sliding friction is prominent in this design, since the outer tips of the vanes have seals that slide on the cylinder walls.
U.S. Pat. No. 3,282,513 describes an engine that has rotating vanes that have sliding seals at the end of the vanes, which slide on cylinder walls. Lubricating oil must be supplied to the seals from the central rotating shafts. This device has some features in common with our single cylinder engine, but our single-cylinder engine has the seals mounted in the wall of the cylinder rather than in the rotating piston, and lubricating oil can be supplied from outside the cylinder rather than through the shaft and piston.
U.S. Pat. No. 2,359,819 is a pump that has sliding seals at cylinder walls. Similarly, U.S. Pat. Nos. 5,228,414, 3,315,648, 3,181,513, 2,989,040, 2,786,455, 1,010,583, and 526,127 describe designs that have rotating members that have seals that slide on cylinder walls.
Since oil supplies are being depleted and the atmosphere is being polluted with greenhouse gases, it is long past time for today""s gasoline engines to be replaced by a more efficient power plant. In accordance with the present invention, which is called xe2x80x9cMECHxe2x80x9d, (acronym for motor, expander, compressor, or hydraulics) a new fluid displacement machine is provided that, with appropriate modifications, can function as an internal combustion engine, an expander (analogous to a turbine), a compressor, a hydraulic motor, or a pump. MECH incorporates rolling friction rather than sliding friction.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention is a motor, expander, compressor, or hydraulic device having in one embodiment an oscillating rotating piston comprising a partial-cylindrical piston having an axis of rotation and end surfaces and defining an oscillating compression volume and expansion volume. An axial sealing member separates the compression volume and the expansion volume and radial seal members seal the end surfaces of the piston. Valves operate to close the compression volume and open the expansion volume at each oscillation of the piston. Means are provided for reversing the rotation of the piston at the end of each cycle of the piston. In advanced embodiments, one or more pistons may be provided that contact other pistons along axial surfaces to form axial seal surfaces with rolling contacts.